Currently, multi-carrier modulation is widely used in the field of communications, which may be achieved by multiple technical means, such as discrete multi-tone (DMT) and orthogonal frequency division multiplexing (OFDM), etc. The multi-carrier modulation employs multiple subcarrier signals, and divides a data stream into several sub-data streams, so that the sub-data streams have much less transmission bit rates, and the data are used to modulate several subcarriers, respectively. Multi-carrier modulation signals are characterized in a relatively low subcarrier data transmission rate and a relatively long code element period. At present, fast Fourier transform (FFT) is an effective way of achieving multi-carrier modulation.
Multi-carrier modulation signals are relatively sensitive to a timing error, which will bring inter-symbol interference (ISI) and inter-channel interference (ICI) to the multi-carrier modulation signals, and degrade signal quality. Hence, timing synchronization needs to be performed to the multi-carrier modulation signals. Wherein, the timing synchronization of the multi-carrier modulation signals includes symbol synchronization (or frame synchronization) and sampling clock recovery. An object of the symbol synchronization is to find a correct FFT window, and an object of the sampling clock recovery is to align a clock of a receiver with a clock of a transmitter, including offset and jitter of clock frequencies.
It should be noted that the above description of the background art is merely provided for clear and complete explanation of the present invention and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background art of the present invention.